[RFC PATCH 2/5] iommu/amd: Configure IRTE to use the GAPPI for posted interrupts

[Sairaj Kodilkar <sarunkod@amd.com>]

When GAPPI is enabled, a guest-mode IRTE with is_run clear delivers a
GAPPI interrupt to the physical APIC ID in the IRTE destination fields,
with the wake vector carried in ga_tag. Program the guest-activated IRTE
accordingly.

Reuse the POSTED_INTR_WAKEUP_VECTOR for gappi which is already reserved
for posted interrupt wakeup handler on x86 and is handled by IDTE entry
sysvec_kvm_posted_intr_wakeup_ipi. Intel VMX already uses same vector
for the wakeup case.

Signed-off-by: Sairaj Kodilkar <sarunkod@amd.com>
---
 arch/x86/kvm/svm/avic.c             |  5 +++++
 drivers/iommu/amd/amd_iommu.h       |  1 +
 drivers/iommu/amd/amd_iommu_types.h |  4 +++-
 drivers/iommu/amd/init.c            |  3 +++
 drivers/iommu/amd/iommu.c           | 21 +++++++++++++++++----
 include/linux/amd-iommu.h           |  1 +
 6 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 7862b13c5409..b666efb5d91c 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -955,6 +955,11 @@ int avic_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
 		} else {
 			posted_intr = !!(entry & AVIC_PHYSICAL_ID_ENTRY_GA_LOG_INTR);
 			pi_data.flags = posted_intr << AMD_IOMMU_FLAG_POSTED_INTR_SHIFT;
+			/* GAPPI is disabled at this point (amd_iommu_gappi is
+			 * enabled in the following patches) hence keep the
+			 * apicid as 0.
+			 */
+			pi_data.apicid = 0;
 		}
 
 		ret = irq_set_vcpu_affinity(host_irq, &pi_data);
diff --git a/drivers/iommu/amd/amd_iommu.h b/drivers/iommu/amd/amd_iommu.h
index 834d8fabfba3..044179cab12e 100644
--- a/drivers/iommu/amd/amd_iommu.h
+++ b/drivers/iommu/amd/amd_iommu.h
@@ -41,6 +41,7 @@ int amd_iommu_enable(void);
 void amd_iommu_disable(void);
 int amd_iommu_reenable(int mode);
 int amd_iommu_enable_faulting(unsigned int cpu);
+extern bool amd_iommu_gappi;
 extern int amd_iommu_guest_ir;
 extern enum protection_domain_mode amd_iommu_pgtable;
 extern int amd_iommu_gpt_level;
diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index f9f718087893..26d7a9796e64 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -113,6 +113,7 @@
 /* Extended Feature 2 Bits */
 #define FEATURE_SEVSNPIO_SUP	BIT_ULL(1)
 #define FEATURE_GCR3TRPMODE	BIT_ULL(3)
+#define FEATURE_GAPPIDISSUP	BIT_ULL(4)
 #define FEATURE_SNPAVICSUP	GENMASK_ULL(7, 5)
 #define FEATURE_SNPAVICSUP_GAM(x) \
 	(FIELD_GET(FEATURE_SNPAVICSUP, x) == 0x1)
@@ -1004,7 +1005,8 @@ union irte_ga_lo {
 		    no_fault	: 1,
 		    /* ------ */
 		    ga_log_intr	: 1,
-		    rsvd1	: 3,
+		    rsvd1	: 2,
+		    gappi_dis	: 1,
 		    is_run	: 1,
 		    /* ------ */
 		    guest_mode	: 1,
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 3bdb380d23e9..2e1889f8a9e4 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -160,6 +160,9 @@ u8 amd_iommu_hpt_level;
 /* Guest page table level */
 int amd_iommu_gpt_level = PAGE_MODE_4_LEVEL;
 
+bool amd_iommu_gappi;
+EXPORT_SYMBOL(amd_iommu_gappi);
+
 int amd_iommu_guest_ir = AMD_IOMMU_GUEST_IR_VAPIC;
 static int amd_iommu_xt_mode = IRQ_REMAP_XAPIC_MODE;
 
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 76f0e469490e..4690cecc9aa7 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -3969,9 +3969,18 @@ static void __amd_iommu_update_ga(struct irte_ga *entry, int apicid, int flags)
 		entry->lo.fields_vapic.is_run = true;
 		entry->lo.fields_vapic.ga_log_intr = false;
 	} else {
-		entry->lo.fields_vapic.is_run = false;
-		entry->lo.fields_vapic.ga_log_intr = !!(flags &
-							AMD_IOMMU_FLAG_POSTED_INTR);
+		bool posted_intr = !!(flags & AMD_IOMMU_FLAG_POSTED_INTR);
+		if (amd_iommu_gappi) {
+			entry->lo.fields_vapic.gappi_dis = !posted_intr &&
+							   check_feature2(FEATURE_GAPPIDISSUP);
+			entry->lo.fields_vapic.is_run = false;
+			entry->lo.fields_vapic.destination =
+						APICID_TO_IRTE_DEST_LO(apicid);
+			entry->hi.fields.destination = APICID_TO_IRTE_DEST_HI(apicid);
+		} else {
+			entry->lo.fields_vapic.is_run = false;
+			entry->lo.fields_vapic.ga_log_intr = posted_intr;
+		}
 	}
 }
 
@@ -4034,7 +4043,11 @@ int amd_iommu_activate_guest_mode(void *data, int apicid, int flags)
 	entry->lo.fields_vapic.guest_mode  = 1;
 	entry->hi.fields.ga_root_ptr       = ir_data->ga_root_ptr;
 	entry->hi.fields.vector            = ir_data->ga_vector;
-	entry->lo.fields_vapic.ga_tag      = ir_data->ga_tag;
+
+	if (amd_iommu_gappi)
+		entry->lo.fields_vapic.ga_tag = POSTED_INTR_WAKEUP_VECTOR;
+	else
+		entry->lo.fields_vapic.ga_tag = ir_data->ga_tag;
 
 	__amd_iommu_update_ga(entry, apicid, flags);
 
diff --git a/include/linux/amd-iommu.h b/include/linux/amd-iommu.h
index 3dd9074e5967..87e76f617ea1 100644
--- a/include/linux/amd-iommu.h
+++ b/include/linux/amd-iommu.h
@@ -82,4 +82,5 @@ static inline bool amd_iommu_sev_tio_supported(void) { return false; }
 #define AMD_IOMMU_FLAG_POSTED_INTR_SHIFT 1
 #define AMD_IOMMU_FLAG_POSTED_INTR  BIT(1)
 
+extern bool amd_iommu_gappi;
 #endif /* _ASM_X86_AMD_IOMMU_H */
-- 
2.34.1